This invention relates to electric toothbrushes, sometimes referred to as mechanical toothbrushes, and is more particularly directed to a portable hand-held, electrically powered, mechanical toothbrush. Specifically, a novel toothbrush having oscillatory movement of a pair of opposed bristle head portions of a dual-head toothbrush is disclosed.
The use of manual toothbrushes has, of course, been know for many years. Indeed, the use of mechanical toothbrushes, typically those which are electrically driven, has been known for a number of years. The purpose, in any event, is to clean the teeth, usually with a toothbrush which comprises a plurality of bristles that are used in conjunction with a dentifrice. Very often, the dentifrice is mildly abrasive.
The dental profession has propounded, for many years, a technique known as the xe2x80x9cBass Techniquexe2x80x9d which, if properly performed, is said to achieve superior results in terms of cleaning one""s teeth using a manual toothbrush. Essentially, the Bass Technique requires the user to position a manual toothbrush over a zone of the teeth, and then to use very short stokes so as to more or less vibrate the brush at that zone where the brush has been located. This short-stroke brushing should continue for a period of timexe2x80x94typically, twenty strokes to forty strokesxe2x80x94so as to remove any foreign material from that zone. The brush is then repositioned and typically another twenty to forty short strokes are performed. Because each zone is very small, the Bass Technique can be very time consuming. Moreover, since it is a requirement that the strokes be very short which, in turn, requires excellent muscle control, exercising the Bass Technique can be very tiring.
The theory is that, at the end of any given stroke, the bristles will flex so as to become oriented in such a manner that the ends of the bristles point generally away from the direction of the travel of the bristles across the teeth. However, at the beginning of the next stroke, in the opposite direction, the still-flexed bristles will then be pointed in the direction of the stroke and this may cause the bristle to chisel the foreign material away from the teeth for a moment before the bristle again begins to flex so as to sweep across the surface of the tooth in the zone where it is located.
However, a more efficacious manner for brushing teeth comprises a variation of the Bass Technique, whereby oscillatory movement is imparted to a toothbrush. Of course, such oscillatory movement is not capable of being executed manually.
A purpose of the present invention is to provide an electromechanical toothbrushxe2x80x94that is, an electrically driven, mechanical toothbrush, most typically referred to as an electric toothbrushxe2x80x94which will permit the user to perform a tooth cleaning procedure which improves upon the Bass Technique by imparting oscillatory movement to the toothbrush. In other words, by using the toothbrush of the present invention, the user will be able to locate the toothbrush at a given zone for a short period of time, while executing a plurality of oscillatory motions of the toothbrush to clean the teeth, and then move on to the next zone, thus achieving efficient cleaning of the teeth.
Apart from the removal of leftover food particles and the like, a particular purpose for cleaning the teeth is to remove plaque build-up from the teeth. Typically, when using a manual toothbrush, plaque build-up is removed much more easily from the buccal surfaces of the teeth than from the lingual surfaces of the teeth, with relatively good foreign material removal from the occlusal surfaces of the teeth also being achieved.
One development that has occurred in respect of manual toothbrushes is the provision of twin-headed brushes, whereby the lingual and buccal surfaces of the tooth can be scrubbed using the bristles of the brush at the same time, with the same stroking action of the brush.
As to electric toothbrushes, most electric toothbrushes provide groups of bristles which are located in concentric circles, where the brush head thus provided is rotated or, more usually, it is reciprocally rotated.
Co-pending application Ser. No. 09/296,631 filed Apr. 23, 1999, now U.S. Pat. No. 6,138,310, teaches a toothbrush having twin heads to which a lengthwise reciprocating linear motion is imparted. A Continuation-In-Part application, Ser. No. 09/510,501 filed Feb. 22, 2000, now abandoned, teaches a twin head or dual-head toothbrush which, however, is such that an oscillatory movement is imparted to the pair of opposed bristle head portions of the brush head. Rotational motion of an electric motor is translated by a motion translation means into oscillatory motion of a drive shaft; the longitudinal axis of the brush head is offset from the longitudinal axis of the drive shaft. In a particular embodiment of that toothbrush, a flywheel is driven from a drive shaft, and it in turn drives a pin which is mated to a cam block.
Several typical prior art toothbrushes are now described. Among them are several manual toothbrushes which comprise dual, opposed bristle heads. They include PORPER U.S. Design Pat. No. D259,977, issued Jul. 28, 1981, which reveals an early design for a toothbrush having opposed bristle heads.
Another manual toothbrush which is adapted for cleaning multiple sides of the teeth at the same time is shown in WAGNER U.S. Pat. No. 5,327,607, issued Jul. 12, 1994. The toothbrush disclosed in that patent includes further bristles which extend from the spine of the toothbrush so as to contact the occlusal surfaces of the teeth at the same as the buccal and lingual surfaces of the teeth are being contacted while the toothbrush is in use.
A typical prior art electric toothbrush is disclosed in AMAKASU U.S. Pat. No. 5,359,747, issued Nov. 1, 1994. Here, a brush member of the toothbrush is given reciprocal motion in the axial direction while, at the same time, the brush member itself is given a rotary motion. The rotary brush member is rotatably mounted on the end of an attachment connected to a drive shaft, and the reciprocating motion in the axial direction thereof is converted into a rotary motion and transmitted to the rotary brush member by a second transmission mechanism.
Another typical prior art electric toothbrush is disclosed in BAUMAN U.S. Pat. No. 5,353,460, issued Oct. 11, 1994. Here, there is a pair of brush elements with driving mechanism which drives one of the brush elements in oscillation, with linkage between the brush elements so that the second brush element is also driven in oscillation. The two brush elements are preferably oscillated in opposite directions. However, the two brush elements can only contact any one surface of the teeth at a time.
A mechanical toothbrush which is said to effectively replicate the Bass Technique is STANSBURY U.S. Pat. No. 5,259,083, issued Nov. 9, 1993. This power driven mechanical toothbrush comprises a plurality of tuft blocks which are mounted on a cam shaft. The tuft blocks are received in sliding relation in a toothbrush head member, and each tuft block slides linearly in a direction parallel to the longitudinal tuft axis as it is guided by guide rails within the head member between a retracted position and an extended position. The tuft blocks are each driven by the rotatable cam. In use, the tuft bristles are brought into contact with the teeth by the user, before the respective tuft block reaches its extended position, so as to thereby flex the bristles and to cause a lateral motion of the distal end of the bristles along the surface of the teeth. This whipping action of the ends of the bristles causes a wiping action across the surface of the teeth while, at the same time, causing a chiselling action by the ends of the bristles against the teeth, so as to thereby remove foreign material away from the teeth in the region where the bristle chiselling action occurs.
Finally, DAUB U.S. Pat. No. 5,027,463, issued Jul. 2, 1991, teaches a toothbrush which may be used for simultaneously brushing and cleaning the occlusal, lingual, and buccal surfaces of the upper and lower teeth of the user. Here, a bristle support member is provided which anchors bristles which extend from the opposite surfaces thereof. The bristles are arranged so that the central rows of bristles are straight while the intermediate and outer rows of bristles on each of the opposed surfaces of the bristle support member are curved. The straight bristles will engage the occlusal surfaces of the teeth, while the intermediate and outer rows will engage the lingual and buccal surfaces of the teeth.
In accordance with one aspect of the present invention, there is provided an electric toothbrush which has a power handle and a brush head portion. The power handle portion is adapted to provide a housing for an electric motor and for a driving mechanism which is located at a first end of the power handle portion. The driving mechanism is powered by the electric motor.
The brush head portion is removably attachable at a first end thereof to the first end of the power handle portion. The brush head portion comprises a pair of opposed bristle head portions arranged so as to present two groups of opposed bundles of bristles disposed substantially perpendicularly each to the other, where each of the groups of bundles of bristles on each respective bristle head portion comprises a plurality of rows and a plurality of columnms of bristle bundles.
The brush head portion of the toothbrush of the present invention comprises a longitudinal hollow shaft portion and a fixed cover portion at a second end thereof which is remote from the first end. The cover portion is shaped and dimensioned so as to overlie the pair of opposed bristle head portions.
The pair of opposed bristle head portions is mounted on a stem so as to form a pair of opposed blocks which extend forwardly from the stem in a direction away from the first end of the brush head portion. The stem has a longitudinal axis, and the pair of opposed blocks are disposed at either side of that longitudinal axis.
The longitudinal axis extends through the shaft portion, and has a coupling at a first end which is adapted to receive vocational driving force from the driving mechanism that is mounted in the power handle portion. The longitudinal drive shaft extends longitudinally through the stem along its longitudinal axis, and has a crank which is formed at the second end of the longitudinal drive shaft remote from the first end.
Drive means are located between each pair of opposed blocks and the underside of a respective region of a fixed cover portion which overlies each respective one of the pair of opposed blocks. The drive means is mounted on the crank so as to have reciprocating motion imparted thereto, as the crank is driven from the drive shaft.
A wedge is formed on the underside of the fixed cover portion in the region overlying each respective one of the pair of opposed blocks. Alternatively, a wedge is formed on the top surface of each opposed block.
In either event, when a reciprocating motion is imparted to the drive means by the crank, the drive means is moved from side-to-side so as to slide from the top towards the bottom of one of the wedges, and from the bottom towards the top of the other of the wedges. That, in turn, imparts an oscillatory movement to the pair of opposed bristle head portions of the brush head.
Typically, the wedges are formed on the underside of the respective region of the fixed cover portion, and the drive means may comprise a pair of link arms, each having the driving cam member formed at the end thereof, and extending in a direction parallel to the longitudinal axis of the stem. The top surface of each of the blocks has a channel formed therein so as to receive and retain a respective one of the driving cam members. Thus, each driving cam member is captured in its respective channel between the respective block and wedge, so as to slide in camming relation therebetween. This, in turn, thereby imparts the oscillatory movement of the pair of bristle head portions about the longitudinal axis of the stem portion.
Specifically, when the wedges are formed on the underside of the respective regions of the fixed cover portion, the drive means may comprise a T-shaped shuttle block which has a substantially planar bottom surface and downwardly and outwardly ramped portions in the upper surface thereof. The ramped portions are dimensioned and located so as to interact with the wedges as reciprocating motion is imparted to the shuttle block, so as to cause sliding wedge action between the wedges and the ramped portions of the shuttle block. The planar bottom surface of the shuttle block then reacts against one or the other of the opposed blocks so as to thereby impart the oscillatory movement of the pair of opposed bristle portions about the longitudinal axis of the stem portion.
Typical materials for the brush head portion are ABS; and for the drive shaft and driving means having the cam members formed at each end, they are typically formed from stainless steel.
If a T-shaped shuttle block is used, it is also typically formed from ABS.
Each of the groups of bundles of bristles on each respective bristle head portion comprises a plurality of rows and a plurality of columns of bristle bundles, where the rows of bristle bundles are aligned parallel to the longitudinal axis of the brush head, and the columns of bristles are aligned perpendicular the longitudinal axis of the brush head.
The bristles in each bundle in each row of bristle bundles on each bristle head portion are substantially equal in length. The length of the bristles in the respective row of bristle bundles on each bristle head portion which is closest to the longitudinal axis of the brush head portion is shorter than the length of the bristles in the respective row of bristle bundles on each bristle head portion which is furthest away from the longitudinal axis of the brush head portion. Moreover, the lengths of the bristles in each respective row of bristle bundles on each bristle head portion are progressively longer in each row of bristle bundles which is further away from the longitudinal axis of the brush head portion than an adjacent row of bristle bundles which is closer to the longitudinal axis of the brush head portion.
Typically, the amount of oscillatory motion by the opposed bristle head portions of the brush head portion about the longitudinal axis of the stem is in the range of 3xc2x0 to 7xc2x0. It is found that motion in the range of 4xc2x0 to 5xc2x0 is particularly effective and gives a good mouth feel.
The rate of oscillatory movement of the opposed bristle head portions of the brush head about the longitudinal axis of the stem is typically in the range of 4,000 to 6,000 oscillations per minute.
A purpose of the present invention is to provide such an electric toothbrush as described above, which can be used to effectively impart the improved version of the Bass Technique to the toothbrush heads and, thereby, to achieve better tooth cleaning results.
Finally, a purpose of the present invention is to bring an electric toothbrush to the market which can be used for very effective cleaning of the teeth, but which can be brought to the market at relatively low cost compared with many of the prior art electric toothbrushes, due to the relatively uncomplicated structure of the electric toothbrush hereof.